1. Field of the Invention
The present invention relates to refrigerator display case doors and frames, and more particularly to refrigerator display case doors and frames formed from composite materials which may allow a door and frame to have better thermal, structural and appearance characteristics.
2. Related Art
Commercial refrigerators and refrigerator display cases are used in markets, food-vending operations, liquor stores and the like for the simultaneous preservation of freshness and attractive display of foods to the customer. Typically, commercial display cases have frames defining an opening for the case which is accessed through large, swinging doors having large areas of multi-layered glazing to permit the customer to see, select and access the refrigerated product easily, while preventing heat transfer into the refrigerated space. Typically, a metal door rail supports and surrounds the multi-layered glazing to support the glazing panels and to protect the edges thereof.
Present commercial glass refrigerator doors typically have door rails which extend peripherally around the glass panels of the doors. Such door rails are used to hold the glass panels in place and extend peripherally around both the inside and outside glass surfaces of the doors.
Door rails have heretofore been formed from extruded or other forms of metal rail elements fastened together at mitered corners of upper and lower horizontal rail members and left and right vertical side members. The hardware for connecting the corners of the rail structures can be complicated, with a significant number of interfitting parts to provide a suitable corner connection. Hinge elements support the door for pivotable movement relative to a vertical axis.
Conventional commercial refrigerated display cases typically also include surrounding frames for defining the opening in the case or unit within which the product is displayed, and which supports the refrigerator doors. The surrounding frame is typically assembled from frame rails typically formed from aluminum components having a decorator strip, extending over the front of the case, a side-wall extending inwardly relative to the case from the decorator strip, the side-walls of the top and bottom rails supporting the hinges for the doors, and a transverse wall for mounting a contact plate against which the magnetic gasket on the door seals. The transverse wall also forms a support for mullions in the display case which contain wiring, ballasts or other hardware for operating lighting units mounted on the surfaces of the mullion extending into the display case. The rearwardly facing portions of the transverse walls also may support raceways or other hardware for equipment used in the unit. The hardware on the rearwardly facing surfaces of the frame are typically difficult to access for servicing, and typically require additional time for assembly, such as for turning an assembled frame over in order to access or assemble the raceways, the mullion elements, and the like.
Frame rails have typically been formed from extruded or other forms of metal fastened together at mitered corners. Such metal rail members may provide an aesthetically pleasing appearance, but are limited in terms of color and texture. While extruded aluminum elements may be formed with different profiles, a large number of frame profiles would require a significantly larger inventory.
The metal frame and door rail members, while providing suitable structural support and pleasing aesthetic appearance, readily conduct heat from outside the refrigerated display case, as well as serving as a condensation surface for water vapor which may be present in the ambient air. To eliminate condensation and fogging, heater wires are sometimes placed in the rail to warm the metal rail and to thus inhibit condensation especially in freezer cases. To change the aesthetic appearance, some rails have been redesigned to place a substantial amount of the metal rail behind the front panel, but there still exists rail material that extends over the front glazing panel.
Combination doors have been made which include metal and plastic, but such doors are typically expensive to manufacture and may include incompatible materials, especially in terms of expansion and contraction rates, and the like. Door and frames have been formed from pultruded materials, but the resulting doors or frames have not been entirely satisfactory. In some situations, covers are still required for the pultruded material to provide an aesthetically pleasing appearance.